In recent years, flat panel displays have been widely used in various commodities and fields, and the flat panel displays are required to have a larger size, a higher image quality, and a lower power consumption.
Under these circumstances, an organic EL display device is attracting considerable attention as an all-solid-state flat panel display with excellent low-voltage driving capability, high-speed responsibility, and self-luminous property. The organic EL display device includes an organic EL element that utilizes the electroluminescence of an organic material.
In an active matrix type organic EL display device, e.g., a thin-film organic EL element is provided on a substrate having TFTs (thin-film transistors). The organic EL element includes an organic EL layer (including a light emitting layer) that is disposed between a pair of electrodes. The TFTs are connected to one of the pair of electrodes. A voltage is applied across the pair of electrodes so that the light emitting layer emits light, thereby displaying images.
In the above conventional organic EL display device, it is known that a sealing film is formed on the organic EL element in order to prevent the degradation of the organic EL element due to moisture and oxygen. Moreover, a laminated film composed of an inorganic film and an organic film has been proposed as the sealing film.
Further, in an apparatus for manufacturing the conventional organic EL display device, the use of a plurality of masks has been proposed to form the laminated film, as described in, e.g., Patent Document 1.